Weed Control

With weeds, education is half the battle.

This page is dedicated to learning about weeds and how to prevent and eliminate them. For weed control advice and products, visit any of our 3 Ace locations.

Weeds are categorized as grassy, broadleaf, annual or perennial. Grassy weeds are best exemplified by crabgrass. Dandelions and plantain are broadleaf weeds.

Annuals die each year but can re-seed themselves. Perennials live for several years. Weed seed can remain dormant in soil for several years and germinate only when growing conditions are right. If you have recently added topsoil, compost or manure to your lawn, you may have given those weed seeds new encouragement.

All grass seed formulations contain some weed seeds. It is nearly impossible to get rid of them. Less-expensive formulations may contain more weed seeds than top-quality seeds. Look for the percentage of "crop" seeds listed on the package for a fair estimate of the number of weed seeds.

Spring is the best time to control broadleaf and grassy weeds—they are smaller and more vulnerable, and weed killers are formulated to work best in cooler weather.

Pre-emergence herbicides lay a chemical barrier on the ground to prevent weeds from germinating. If soil is disturbed after a pre-emergence killer has been applied, the protective barrier can be lost. Do not rake or de-thatch lawns after applying pre-emergence herbicides.

Follow these three steps when applying herbicides:

Remove trash, leaves and excess dead grass from lawn. If power raking (de-thatching) is planned, do it as part of lawn preparation.

Apply the pre-emergence product as directed. Distribute evenly. Spread at half rate in both directions to assure even distribution. This is better than spreading at full rate in just one direction.

After application, water the lawn. Watering moves the chemical into the soil where it can work on germinating weed seeds. In flower beds or around trees and shrubs, weeds can be stopped with weedshields. These are made of heavy-duty plastic and are used under decorative bark or rock.
Applying Chemicals

The best defense against weeds is a lawn so thick with grass that weeds don't have a chance. However, that seldom happens, so the home gardener needs help from safe, effective chemicals.

The ways in which chemicals can be applied are:

Emulsifiable concentrates - liquids that are diluted with water to proper strength. Most have an oil base.

Wettable powders - very fine dusts that must be mixed with water. They are applied through sprayers as are emulsifiable concentrates.

Dusts - powdered forms of chemicals, usually with the particles noticeably larger than in wettable powders. They are applied with a shaker, duster, etc. and adhere to the foliage to which they are applied.

Granules - similar to dusts, but with still larger particles. In a granule, the chemical becomes available to the living plant by breaking down the granule or by releasing the active ingredient. Granules are usually spread with a lawn spreader. Weather and moisture provide the slower chemical-release action.

Systemic chemicals - available in both liquid and dry form can be used in combination with fertilizers to provide pest control as well as plant nutrition. Systemic chemicals are absorbed by plants or lawn and cannot be washed off by sprinkling or rain.

At least one manufacturer packages insecticide in a one-piece plastic sprayer. The concentrated insecticide is premixed and ready to use, eliminating the chance of getting chemicals on the user's skin. After application, the sprayer is thrown away.

Liquids of the hormone-type weed killers are normally esters or amine salts. Ester formulations may be high volatile or low volatile, which means they do or do not vaporize easily.

Low-volatile esters release a minimum amount of fumes at temperatures below 85°F; high-volatile esters give off fumes at lower temperatures. However, air temperature can be somewhat misleading since temperature at the lawn surface can be 20° to 40° higher.

No ester formulation is safe to use around ornamentals because of vapor hazard. Salt formulations are less hazardous because they do not give off damaging fumes. However, wind movement of spray particles is equal on both esters and salts.

Be sure to check manufacturer's literature for more data on each type of chemical. Under no circumstances should a homeowner control weeds with highly toxic products bearing the skull and crossbones and the word "DANGER" on the label.